Biology subjects

Tsankova, N. M.

Publications and source records attributed to Tsankova, N. M..

9 recordsLinked to original sources

bioRxiv2026

Aquaporin-4 Regulates Edema, Sustains Astrocyte Differentiation, and Constrains Immunosuppressive Remodeling in Glioblastoma

Vasogenic cerebral edema is a severe complication that affects most patients with glioblastoma (GBM). It leads to an increase in intracranial pressure, neurological deficits, and increased mortality rates. While there is considerable research on edema formation, the molecular and cellular mechanisms of edema resolution in GBM, particularly in response to dexamethasone or other anti-edema therapies, remain largely undefined. Our findings demonstrate that the water channel aquaporin-4 (AQP4), a key regulator of brain water homeostasis, is upregulated in human GBM compared to the normal brain. AQP4 expression correlates with peritumoral edema in GBM patients, with the classical (CL) GBM subtype exhibiting the highest AQP4 levels but the lowest edema content relative to the proneural (PN) and mesenchymal (MES) subtypes. Using the RCAS/tv-a system, we generated de novo GBM with defined driver mutations in Aqp4-proficient and -deficient mice. Loss of Aqp4 shortened survival and exacerbated edema, accompanied by reduced astrocytic coverage within the tumor core, but not at the tumor margin. Single-cell RNA-sequencing and spatial transcriptomics revealed that Aqp4 loss reprograms astrocytes toward an immature, progenitor-like state and alters their crosstalk with other cell types in the GBM microenvironment. Additionally, loss of Aqp4 skewed myeloid populations toward immunosuppressive phenotypes while reducing lymphoid infiltration. Treatment with anti-VEGFA antibody, an established anti-edema therapy, increased expression of Aqp4 and reduced vessel leakage, underscoring the role of AQP4 in the therapeutic modulation of brain water balance. Overall, this study highlights the important role of AQP4 in resolving edema and its critical function in maintaining astrocyte identity and shaping the immune landscape of GBM.

cancer biology↗

bioRxiv2025

Guidance receptor-mediated mechanocompliance of GBM cells facilitates immune-silent invasion

The lethality of glioblastoma (GBM) stems from diffuse infiltration and immune evasion, two hallmarks traditionally studied separately. Here, we identify as unifying mechanism how GBM cells utilize guidance receptors Plexin-D1 and Plexin-B2 to gain mechanocompliance, i.e., the ability to deform and remodel membrane/cytoskeleton during confined migration without triggering immune activation. We show that PLXND1 upregulation marks invasive fronts and predicts poor survival of glioma patients. Through live-cell imaging in microchannels, intracranial xenografts, single-nucleus transcriptomics, and lipidomics we demonstrate that Plexin-D1/B2 enable GBM cells to retract tumor microtubes (TMs), traverse constrictions, and escape microglial surveillance. Single and especially double deletion of PLXND1 and B2 resulted in TM overgrowth, membrane instability, and susceptibility to cell fragment shedding, leading to impaired migration and a shift to activation of tumor-associated myeloid cells. Our findings thus reveal a molecular strategy used by GBM cells to penetrate through interstitial space while escaping immune surveillance. SIGNIFICANCEPlexin-mediated mechanocompliance underlies the invasive yet immune-silent behavior of GBM cells, exposing a vulnerability that could be therapeutically exploited by forcing invading tumor cells into a mechanically fragile, immunogenic state.

cancer biology↗

bioRxiv2025

Cortical tension as a mechanical barrier to safeguard against premature differentiation during neurogenesis

Neuronal differentiation requires coordinated gene reprogramming and morphodynamic remodeling. How mechanical forces integrate with nuclear gene programs during neurogenesis remains unresolved. Here, we identify cortical tension as a mechanical barrier that safeguards against premature neuronal differentiation. Deletion of Plexin-B2, a guidance receptor controlling actomyosin contractility, lowers this barrier, enabling neurite outgrowth and accelerating neuronal lineage commitment. We show that coupling of extrinsic differentiation cues with intrinsic morphodynamics is essential for stabilizing neuronal fate and that cortical barrier and epigenetic barrier act in concert to regulate developmental timing. In cerebral organoids, Plexin-B2 ablation triggered premature cell-cycle exit and differentiation, resulting in progenitor pool depletion and neuroepithelial disorganization, phenotypes echoing intellectual disability in patients with rare pathogenic PLXNB2 variants. Our studies demonstrate that cortical tension functions as mechano-checkpoint that regulates the onset of neurogenesis. Lowering this barrier may provide a strategy to accelerate induced neuron generation and maturation for CNS disease modeling.

neuroscience↗

bioRxiv2024

Spatial multi-omics defines a shared infiltrative signature in glioblastoma at the resection margin

Glioblastoma (GBM) remains an untreatable disease. Understanding GBMs infiltrative biology at the resection margin is limited, despite causing disease recurrence and progression. To address this, we generated a high-throughput single-nucleus (sn)RNA-seq and snATAC-seq multi-omic dataset from six tumors with distinct genomic drivers and combined it with spatial transcriptomics to characterize the unique molecular phenotype of GBM near the margin. By contrasting GBM-specific biology in matching "Core" vs. "Margin" dissections, we define unique, shared "GBM infiltration" and chromatin accessibility signatures near the margin. We prioritize EGFR as a top differentially expressed and accessible "Margin" marker across GBM subtypes, show its dynamic expression along a core-to-margin infiltration trajectory, and validate its role in migration through CRISPR/Cas9 deletion in two patient-derived models. ChIP-seq studies furthermore corroborate preferential TEAD1 binding at EGFRs accessible regulatory elements. This validated multi-omic dataset enables further studies into tumor and microenvironment biology in the context of residual GBM disease.

cancer biology↗

bioRxiv2023

R-loop landscapes in the developing human brain are linked to neural differentiation and cell-type specific transcription

Here, we construct genome-scale maps for R-loops, three-stranded nucleic acid structures comprised of a DNA/RNA hybrid and a displaced single strand of DNA, in the proliferative and differentiated zones of the human prenatal brain. We show that R-loops are abundant in the progenitor-rich germinal matrix, with preferential formation at promoters slated for upregulated expression at later stages of differentiation, including numerous neurodevelopmental risk genes. RNase H1-mediated contraction of the genomic R-loop space in neural progenitors shifted differentiation toward the neuronal lineage and was associated with transcriptomic alterations and defective functional and structural neuronal connectivity in vivo and in vitro. Therefore, R- loops are important for fine-tuning differentiation-sensitive gene expression programs of neural progenitor cells.

genomics↗

bioRxiv2022

Multi-omic profiling of the developing human cerebral cortex at the single cell level

The cellular complexity of the human brain is established via dynamic changes in gene expression throughout development that is mediated, in part, by the spatiotemporal activity of cis-regulatory elements. We simultaneously profiled gene expression and chromatin accessibility in 45,549 cortical nuclei across 6 broad developmental time-points from fetus to adult. We identified cell-type specific domains in which chromatin accessibility is highly correlated with gene expression. Differentiation pseudotime trajectory analysis indicates that chromatin accessibility at cis-regulatory elements precedes transcription and that dynamic changes in chromatin structure play a critical role in neuronal lineage commitment. In addition, we mapped cell-type and temporally specific genetic loci implicated in neuropsychiatric traits, including schizophrenia and bipolar disorder. Together, our results describe the complex regulation of cell composition at critical stages in lineage determination, serve as a developmental blueprint of the human brain and shed light on the impact of spatiotemporal alterations in gene expression on neuropsychiatric disease. One-Sentence SummarySimultaneous profiling of gene expression and chromatin accessibility in single nuclei from 6 developmental time-points sheds light on cell fate determination in the human cerebral cortex and on the molecular basis of neuropsychiatric disease.

neuroscience↗

bioRxiv2021

A comprehensive series of temporal transcription factors in the fly visual system

The brain consists of thousands of different neuronal types that are generated through multiple divisions of neuronal stem cells. These stem cells have the capacity to generate different neuronal types at different stages of their development. In Drosophila, this temporal patterning is driven by the successive expression of temporal transcription factors (tTFs). While a number of tTFs are known in different animals and across various parts of the nervous system, these have been mostly identified by informed guesses and antibody availability. We used single-cell mRNA sequencing to identify the complete series of tTFs that specify most Drosophila medulla neurons in the optic lobe. We tested the genetic interactions among these tTFs. While we verify the general principle that tTFs regulate the progression of the series by activating the next tTFs in the series and repressing the previous ones, we also identify more complex regulations. Two of the tTFs, Eyeless and Dichaete, act as hubs integrating the input of several upstream tTFs before allowing the series to progress and in turn regulating the expression of several downstream tTFs. Moreover, we show that tTFs not only specify neuronal identity by controlling the expression of cell type-specific genes. Finally, we describe the very first steps of neuronal differentiation and find that terminal differentiation genes, such as neurotransmitter-related genes, are present as transcripts, but not as proteins, in immature larval neurons days before they are being used in functioning neurons; we show that these mechanisms are conserved in humans. Our results offer a comprehensive description of a temporal series of tTFs in a neuronal system, offering mechanistic insights into the regulation of the progression of the series and the regulation of neuronal diversity. This represents a proof-of-principle for the use of single-cell mRNA sequencing for the comparison of temporal patterning across phyla that can lead to an understanding of how the human brain develops and how it has evolved.

developmental biology↗

bioRxiv2020

Cell type-specific isolation and transcriptomic profiling informs glial pathology in human temporal lobe epilepsy

The pathophysiology of epilepsy underlies complex network dysfunction, the cell-type-specific contributions of which remain poorly defined in human disease. In this study, we developed a strategy that simultaneously isolates neuronal, astrocyte and oligodendroglial progenitor (OPC)-enriched nuclei from human fresh-frozen neocortex and applied it to characterize the distinct transcriptome of each cell type in temporal lobe epilepsy (TLE) surgical samples. Differential RNA-seq analysis revealed several dysregulated pathways in neurons, OPCs, and astrocytes, and disclosed an immature phenotype switch in TLE astrocytes. An independent single cell RNA-seq TLE dataset uncovered a hybrid population of cells aberrantly co-expressing canonical astrocyte and OPC-like progenitor markers (GFAP+OLIG2+ glia), which we corroborated in-situ in human TLE samples, and further demonstrated their emergence after chronic seizure injury in a mouse model of status epilepticus. In line with their immature signature, a subset of human TLE glia were also abnormally proliferative, both in-vivo and in-vitro. Generally, this analysis validates the utility of the proposed cell type-specific isolation strategy to study glia-specific changes ex vivo using fresh-frozen human samples, and specifically, it delineates an aberrant glial phenotype in human TLE specimens.

neuroscience↗

bioRxiv2019

Plexin-B2 is a key regulator of cell mechanics during multicellular organization

During multicellular organization, individual cells need to constantly respond to environmental cues and adjust contractile and adhesive forces in order to maintain tissue integrity. The signaling pathways linking biochemical cues and tissue mechanics are unclear. Here, we show that Plexin-B2 regulates mechanochemical integration during multicellular organization. In human embryonic stem cells (hESCs), Plexin-B2 controls cell shape and tissue geometry in both 2D epithelial colony and 3D spheroid aggregates by regulating actomyosin contractility and junctional/cell-matrix adhesive properties. Atomic force microscopy (AFM) directly demonstrates that Plexin-B2 modulates cell stiffness in hESC colonies, which in turn impacts cell proliferation and cell fate specification through {beta}-catenin signaling and YAP mechanosensing. YAP also functions as a mechanoregulator downstream of Plexin-B2, thus forming a mechanochemical integrative loop. In human neuroprogenitor cells (hNPCs), Plexin-B2 similarly controls cell stiffness and tensile forces, as revealed by AFM and FRET tension sensor studies. Strikingly, Plexin-B2-deficient hNPCs display accelerated neuronal differentiation. From an organogenesis perspective, Plexin-B2 maintains cytoarchitectural integrity of neuroepithelium, as modeled in cerebral organoids. On a signaling level, Plexin-B2 engages extracellular as well as intracellular Ras-GAP and RBD domains for mechanoregulation through Rap and Rac GTPases. Our data unveil a fundamental function of Plexin-B2 for mechanochemical integration during multicellular organization, and shed light on the principle of force-mediated regulation of stem cell biology and tissue morphogenesis.

developmental biology↗